Forced air furnace advice

[maple1]

If your return air does not have an unobstructed path back to the furnace, the blower could in effect try to pull air down the chimney. Quick dirty & simple explanation.

 

[brenndatomu]

I'm not sure I understand the negative pressure thing. Can you explain it better?

If your return air does not have an unobstructed path back to the furnace, the blower could in effect try to pull air down the chimney. Quick dirty & simple explanation.

Yup, that is the basics of it.
I'll get a little more detailed if ya are into that.
The draft setting that SBI calls for is -.04" Water Column to -.06"WC (-.04"WC to -.06"WC) What that means is when comparing atmospheric pressure in the basement VS in the chimney, the chimney has a (very) small negative pressure (or vacuum), that is what makes the whole firebox work. The old saying is that the chimney is the engine that drives the stove. Anyways, If you have a situation where the blower does not have unrestricted flow (return air) coming from the heated area, it will pull a small negative pressure on the basement...that competes against the chimney and can cause all kinds of trouble. The least of your troubles would be if the furnace just performed (burned) weak, worst case is smoke in the house.
That brings up another point too, you will need to get a manometer to measure your draft. It can also be used to set the static pressure (supply duct air speed) in the ducts. The one that is most commonly used by us cheap ole wood burners is a Dwyer Mark II model 25. You can find 'em reasonable on fleabay and others...or, I just happen to have some for sale over in the Hearth.com "for sale/wanted" forum right now.

And you thought putting a wood burner was gonna be easy

 

[brenndatomu]

A couple questions. Just curious what your final chimney height ended up being?
Did you just get the Tundra? If so what serial #/build date do you have?

 

[Matt78]

OK. Makes sense I guess. Does leaving the basement door open help? Your right I didn't think there wasn't going to be all this work. But it should be worth it.

I went 18' from the tee up

I do have a manometer. I'll save the questions about using that for later. Lol

I actually seen a post of yours back in January or February that menards had them on sale. I bought it the same day. My serial number is 1144. Is there anything I should be aware of? I did read of some issues with furnace. Thanks again for all the info

 

[Matt78]

Build date is 7/8/2014 (#2689955)

 

[Matt78]

Can you tell me anything about the furnace?

 

[brenndatomu]

Can you tell me anything about the furnace?

Sure, there are a number of Tundra owners here, what do you wanna know?

 

[Matt78]

Mostly how to operate it. I know it needs dry wood. Did drolet get all the issues ironed out? I remember reading of some issues. Can't exactly remember what they where. I also read where someone was using a sauna timer and a thermastat. Is this so when you fire a new load. The draft can be open untill everything is up to temp. Then after time runs out on timer it goes back to using the thermastat? When using the manometer. You just drill hole into black stove pipe and check draft. This is done after chimney is up to temp?

Thanks again for taking time to answer my questions. I've never used a furnace. Only wood burners. And none of which were EPA stoves.

 

[brenndatomu]

Did drolet get all the issues ironed out?

They say so...we'll see.

I also read where someone was using a sauna timer and a thermastat. Is this so when you fire a new load. The draft can be open untill everything is up to temp.

Yeah, you have the idea. I used a 15 minute bathroom fan timer. The factory switch works but the timer is just a convenience factor, or idiot proofing in some cases
On the EPA fireboxes you need to get them up to temp for the secondary burn to work. Then when the damper closes it is off to the races if you are using dry wood. The less the intake damper is open (once up to temp) the longer the wood lasts.
Start with some kindlin when you have a cold firebox. Don't expect much the first couple fires, seems like the firebrick has to dry out.
You'll have the high temp paint curing smell too, so it's good if you can do the first fire or two on days where it is not too cold and you can open the windows. Thing about warm days is the chimney draft will be low and it won't burn the best...just so you know. Every chimney/house is different but I would guess with your setup anything much over 40* will start causing you low draft issues, just a rough guess.

When using the manometer. You just drill hole into black stove pipe and check draft. This is done after chimney is up to temp?

Yup, pretty much. You need to test before the pipe damper, not after. If you have the Dwyer manometer it will need to be flat and level, and zeroed out before putting the tube in the pipe. Get a short piece of metal tube to attach the meter hose to, then that goes in the pipe, not the hose, seems obvious but people have done it.
Your welcome. You'll love it once you get used to it...oh, more pics please

 

[DoubleB]

My serial number is 1144.

Hi @Matt78 ,
Hate to say it but I'm not optimistic that your furnace with that serial number and build date is solved from cracking (if that's what you were wondering about).

I assume you're watching the bigger Tundra thread over at:
https://www.hearth.com/talk/threads/everything-drolet-tundra-heatmax.140788/page-15.

If your furnace has the parts 72 and 73 that @brenndatomu shows in post #359, then you have the updated furnace that we hope will avoid the cracking (but time will tell). Assuming you don't have those parts (firebrick), then it appears that your furnace is at higher risk of cracking. You can do nothing and hope cracks don't form; do nothing and rely on SBI's warranty if they do; add firebrick yourself; avoid the thermostat and rely on the bathroom timer to minimize the damper open; and/or add some kind of over temp protection to shut the damper. You can find discussion on all of this over on that other thread, although it will take some time to review it all.

 

[Matt78]

Well no I didn't read that about the cracking! Yikes! I think I may add some fire brick that I believe doubleb added. There was another fella that had a temp control on the flue stack. I may try that also. I contacted him about his setup.

Wasn't there some other issues with the blower filter box and the ash pan? Should I be worried about that? Starting to think I should of saved up for a better furnace. But I'm in so we'll see I guess.

We've had a family member come down with stage four cancer. So I haven't messed with furnace to much this week. Maybe get back at it next week.

 

[brenndatomu]

Wow, sorry to hear about your family member!
You need not worry about the ash drawer issue, they took care of that long ago, I don't think too many people use the ash drawer anyways.
If you add the extra firebrick in the front you should be fine, especially if you do the temp control. I have the parts to do that on mine...gotta get it wired up before "fire in the hole" in a month or so...

 

[DoubleB]

Yes, I'm sorry to hear about your family member. I'm glad you can be there to help.

Starting to think I should of saved up for a better furnace.

Possibly. But at least if anything does go wrong you might end up with a free furnace assuming they warranty it. And, with firebrick and/or a temp controller, you ought not have cracking problems. If I get my act together I'll post on the other thread about the simple temp control that I did last spring--simply replaced the factory 160F high temp snap disk with a ~125F snap disk. Seemed to work pretty well to prevent the damper from staying open more than a few minutes once the furnace was up to cruising speed. I haven't tested it long enough yet to fully form an opinion on it though.

Best Regards.

 

[Matt78]

Hey guys getting ready to plan how I'm going to run ducting. Remember I'm planing on doing a couple of temporary runs till I can have everything tied together. My first Idea is to put two or three runs at one end of the house. The gas furnace thermastat would be towards other end of house. Other idea is to put one run at one end of house and another at the other end. My house Is 1850 sq ft ranch style with a open flor plan. Again any imput would be great.

 

[brenndatomu]

I'd put one run to each end unless you want cooler bedroom area or something. You can always turn the gas furnace tstat down a few degrees to keep it from kicking on. Keep in mind you will want dampers in the duct or adjustable register covers (or both) to set your static pressure and balance the air flow

 

[Matt78]

I think I'm going to put two at one end and one towards end with bedroom and bathroom. What is standard gauge that menards sells? I would want to get 26 gauge 8" round pipe right? What kind of ctc would I need maintain?

 

[brenndatomu]

Double check the manual but I think it is 6" for the first 6' then 1" after that

 

[brenndatomu]

I think I'm going to put two at one end and one towards end with bedroom and bathroom. What is standard gauge that menards sells? I would want to get 26 gauge 8" round pipe right? What kind of ctc would I need maintain?

Yeah, 26, 28, whatever they stock works fine. You are gonna run (3) 8" runs? Drolet recommends only using 2 of the duct connections, preferably the two on the sides. I'd do two main runs and just come off the 8" with 6" taps for the registers if you need multiples

 

[Matt78]

I'm using the 2 on sides of furnace. Then split it off to the two registers. I noticed menards sells 26, 28, and standard. Maybe standard is 30? Man this furnace stuff is complicated! Maybe I should of put a insert in the fireplace. I'm sure it will be worth it.

 

[Matt78]

Can I run the two 8" pipes out of furnace then connect them to each other using 90* tees? Then do 6" pipe off of that? The 8" will run the length of house, but be feed with both pipes coming from furnace.

 

[brenndatomu]

Man this furnace stuff is complicated! Maybe I should of put a insert in the fireplace

Just do both...I did
I guess I have WHAD (wood heater acquisition disorder)

Can I run the two 8" pipes out of furnace then connect them to each other using 90* tees? Then do 6" pipe off of that? The 8" will run the length of house, but be feed with both pipes coming from furnace.

Ahh, hmm, I hafta think about that a bit. What would be the advantage?

 

[Wisneaky]

Just do both...I did
I guess I have WHAD (wood heater acquisition disorder)

Ahh, hmm, I hafta think about that a bit. What would be the advantage?

Could do a plenum like I did on the one I had.

 

[maple1]

Can I run the two 8" pipes out of furnace then connect them to each other using 90* tees? Then do 6" pipe off of that? The 8" will run the length of house, but be feed with both pipes coming from furnace.

I don't think I would do that.

 

[Matt78]

Brenn
Just thinking out of the box I guess. I'll run em separate and run 6" runs off the 8".